1. Field of the Invention
The present invention relates to wrappers for smoking articles such as cigarettes and especially to such wrappers which reduce the tendency of cigarettes to cause ignition of surfaces which come in contact with the lit cigarette. Reports have been made of fires attributed to burning cigarettes coming in contact with combustible materials. Such reports have generated interest in reducing the tendency of cigarettes to ignite surfaces and materials included in furniture, bedding, and the like upon contact. One obviously desirable attribute of cigarettes in this regard would be that they extinguish themselves if left unattended for a period of time whether in an ash tray or in open air. Since it is recognized by those skilled in the art that the wrapper construction for the cigarette strongly influences the behavior of the cigarette during smolder, modification of the wrapper to achieve these desired results would be highly beneficial. In particular, a wrapper construction that does so without serious detrimental effects on desired smoking properties and characteristics would be especially advantageous. The present invention is directed to such wrapper constructions and improved smoking articles utilizing them.
2. Description of the Prior Art
The subject of reducing the tendency of cigarettes to ignite upholstery, bedding, and the like has received much attention.
Considerable effort has been directed to modifications of cigarette papers for the purpose of reducing fire hazards, including the development of non-burning wrappers, for example, as disclosed in U.S. Pat. No. 4,044,778 to Cohn dated Aug. 30, 1977.
It is also known, as in U.S. Pat. No. 4,231,377 to Cline dated Nov. 4, 1980, for example, to treat conventional wrappers with chemical adjuvants such as alkali metal citrates to control burn properties.
It is, moreover, known as described in copending and coassigned U.S. patent application Ser. No. 334,120 filed Dec. 24, 1981 now U.S. Pat. No. 4,461,311 issued July 24, 1984 to Mathews, DeLucia and Durocher that the addition of extraordinary amounts of burn promotion additives to cigarette paper leads to a reduced emission sidestream smoke. Cigarettes made with such papers normally would not have self-extinguishing properties, however.
Additionally, copending and coassigned U.S. patent application Ser. No. 627,711 filed July 11, 1984 now U.S. Pat. No. 4,615,345 issued Oct. 7, 1986 to D. F. Durocher describes wrapper constructions with specially designed paper structures and patterned application of burn enhancing compositions that yield cigarettes which self-extinguish in a predetermined amount of time if not puffed. Such cigarettes, however, require nonconventional cigarette wrappers as well as additional chemical additives which may affect taste.
U.S. Pat. No. 1,555,320 to Weil dated Sept. 20, 1925 describes a cigarette having one or more bands of tobacco leaf or treated paper to cause the cigarette to extinguish when discarded. Other patents having paper or board bands in various configurations are described in U.S. Pat. Nos. 2,666,437 to Lattof dated Jan. 19, 1954, 2,335,432 to Millet dated Nov. 30, 1943, and 1,581,451 to Knapp dated Apr. 20, 1926.
In summary it remains desired to produce wrapper constructions for cigarettes and the like that would result in a cigarette with reduced propensity to ignite substrates and a cigarette which reliably self-extinguishes in air after burning for a specified and controlled period of time. It is further desired to produce such wrapper constructions that accomplish this objective using conventional materials and without significant deleterious effects on desired smoking properties.